Silicone rubber compositions and long-term-stress-resistant silicone elastomers obtained therefrom

Inactive Publication Date: 2006-08-24
WACKER CHEM GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0015] It is therefore an object of the present invention to provide crosslinkable silicone compositions with basic constituents in such a way that, witho

Problems solved by technology

However, repeated dynamic mechanical stress cycles generally lead unavoidably to continually increasing mechanical fatigue and damage to all elastomer materials, and this ultimately leads to a loss of function of the elastomer component.
However, the presence of organophosphorus compounds in silicone compositions or silicone elastomers has a number of disadvantages.
For example, platinum-catalyzed addition crosslinking is inhibited, compression set is higher, thermal stability is reduced, and undesirable, and at times, toxic decomposition products are formed upon heating.
However, a disadvantage is that the preparation of the required siloxanols, which proceeds via a palladium-catalyzed hydrolysis step, is relatively complicated.
A disadvantage is the relatively complicated preparation of carbinol-functional siloxanes.
In addition, such compounds have a thixotropic effect, i.e. the flowability of the silicone composition is considerably impaired.
Furthermore, the relatively long-chain alkylene spacers in the carbinol-fun

Method used

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Examples

Experimental program
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examples

[0075] The viscosities reported below were determined at a temperature of 25° C. and a shear rate of 1 sec−1. The plasticity of the polymers was determined in a Brabender Plastograph at 25° C. and 60 revolutions per minute. M2 denotes a dimethylsiloxy unit, and VM denotes a methylvinylsiloxy unit.

[0076] The preparation of the polydiorganosiloxanes (A) according to the invention and not according to the invention was firstly carried out by the following methods. The properties of the polymers P1 to P10, derived from the 1H- or 29Si-NMR spectrum, are summarized in Table 1.

[0077] Polymer P1: In a 3 1 Sigma kneader, 1300 g of a dimethylpolysiloxane which has an Si-bonded hydroxyl group in each of the terminal units and a viscosity of 140 mPa·s, 18 g of a dimethylvinylsiloxy-terminated dimethylpolysiloxane having a viscosity of 174 mPa·s 3.68 g of a low molecular weight copolymer of dimethylsiloxy and methylvinylsiloxy units which has a hydroxyl group in each of the terminal units and ...

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Abstract

The present invention relates to silicone rubber compositions and long-term-stress-resistant silicone elastomers obtained therefrom, which have excellent resistance to long-term dynamic mechanical stresses, and to their use.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to silicone rubber compositions and to long-term-stress-resistant silicone elastomers obtained therefrom which exhibit excellent resistance to long-term dynamic mechanical stresses, and to their use. [0003] 2. Background Art [0004] Silicone elastomers are frequently used in applications which are associated with high dynamic mechanical stresses. Examples are oscillation dampers, resonance dampers, exhaust and catalyst suspension elements, and engine mounts in automobiles. Further examples include mountings for movable parts in machine construction, peristaltic pump tubing in the medical field, diaphragms, valves, and in particular, keypads commonly used in the electronics field. To maintain the function of these silicone elastomer components, it is particularly important that the mechanoelastic properties either exhibit no change or change only slightly when dynamic mechanical stress is...

Claims

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Application Information

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IPC IPC(8): B32B25/00C08L83/04B32B9/04
CPCC08G77/20C08G77/44C08K5/5425C08K2201/006C08L83/04C08L83/00Y10T428/31663D06B3/10D06B19/0011D06B19/0029D06C7/00D06C27/00
Inventor ACHENBACH, FRANKFEHN, ARMIN
Owner WACKER CHEM GMBH
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